1.2 Hydrosphere Flashcards
V shaped valley
Steep gradient forces water flow downslope, vertical erosion cuts into valley
Vertical erosion in form of hydraulic action- force of water breaks material off bank
Abrasion- scraping of bed by transported material
Solution- chemicals in water dissolve minerals in rock
Vertical erosion exposes sides of valley and are weakened by weathering
De-stabilised rock falls into river and flows downstream, adds to erosive river power
Steep-sided V shaped valley forms with narrow walls
Resistant rocks in upland areas means valley sides barely erode
When river meets hard rock, it winds round it and takes path of soft rock
Narrow necks of interlocking spurs extending to either side of river valley are left
Waterfall
River moves over hard rock onto a layer of soft rock
Soft rock begins to erode quicker than hard rock due to differential erosion, creating a step
River erodes from hydraulic action- force of water breaks material off bank
Abrasion- scraping of bed by transported material
Solution- chemicals in water dissolve minerals in rock
River undercuts soft rock, leaving an unsupported overhang, falls into plunge pool
Rock swirls around in river, deepening plunge pool
Occurs most during high discharge when hydraulic action is greatest
Waterfall retreats upstream and a steep sided gorge is cut back into hillside
Meander and Ox-bow lake
Lateral erosion on outside bank where water flows fastest as bed is smoother
Outside bank erodes from hydraulic action- force of water breaks material off bank
Abrasion- scraping of bed by transported material
Solution- chemicals in water dissolve minerals in rock
Neck of land narrows as two bends in river are eroded towards each other
Slow water on inside bank causes deposition of material, creating a slip-off slope
Increased discharge enhances erosion, cutting through neck of land
Deposition seals old meander, making a new straight river channel
River takes shortest route leaving old meander isolated, forming an ox-bow lake
Ox-bow lake will fill up with sediment and dry up
Hydrological cycle within a drainage basin
Inputs:
Precipitation mainly through rain and snow
Intensity of precipitation- increased surface run-off (ground can’t absorb water quick enough)
Outputs:
Water evaporates, heat intensity from the sun
Transpiration- water lost through surface of vegetation and evaporates
Storage:
Water stored in soil and vegetation as groundwater storage
Water reaches groundwater storage by infiltration, when water filters into soil
Transfers:
Surface run-off- excess water can’t be infiltrated, lead to flooding
Stemflow- water intercepted by vegetation, runs down branches and stems
Hydrographs- physical + human
Steeper slope leading to basin- water flows faster to river
More vegetation intercepts rain- slows movement of water to river
Water reaches river quicker- smaller size of basin, less distance to travel
Impermeable rock reduces percolation- soil becomes saturated quickly
More drains quickly deliver rain to river- increases groundwater flow to river
Tarmac prevents infiltration (impermeable)- creates fast surface run-off
Less trees in area- doesn’t allow interception on vegetation
Compacted soils from farming reduces saturation in ground- prevents infiltration
